There is disclosed a vane-type rotary compressor provided with a rotary sleeve which is interposed between a center housing and a rotor and supported by compressible fluid for rotation with a plurality of vanes by Tokkyo Kokai Koho (Japanese Published Unexamined Patent Application) Sho 58-65988. The compressor is particularly suitable for use with an automobile engine required to operate over a wide speed range because of being substantially free from frictional heat as well as wear at the apex of each vane. However, there is the possibility of scuffing and seizure troubles if air is highly compressed in the compression working space within the compressor to push the rotary sleeve from within to the inner periphery of the center housing. From a study on the movement of the rotary sleeve, it has been clarified with the rotary sleeve has its center moved along not a straight line but an ellipitical figure to contact the compression side inner periphery of the center housing and that the outer periphery of the rotary sleeve touches the inner periphery of the center housing not at a particular point but on a broad area, which is variable in accordance with the number of vanes and the position of a discharge port. The compression working space is defined by two adjacent vanes to have the maximum pressure immediately before it opens to the discharge port. The maximum pressure suddenly drops when immediately after the compression working space is vent to the discharge port. This is the reason the rotary sleeve makes an irregular motion and touches the compression side inner periphery of the center housing on the aforementioned contact area. Besides, the rotaty sleeve also makes another irregular motion to contact the suction side inner periphery of the center housing whenever the engine speed or rotor speed suddenly changes.
It is the primary object of the invention to provide an improved vane-type rotary compressor in which a rotary sleeve is prevented from contacting the inner periphery of the center housing when it is pushed toward the compression side by compressed air in the compressor and free from irregular motion when the engine speed suddenly changes.